Transcript The Universe

The Universe
Mr. I
Physical Science
History of The Universe
• All started with the Big Bang Theory approximately 12-14 Billion Years
ago according to NASA.
The Big Bang Theory
• The Big Bang Theory States that all the matter in the universe was once condensed into
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a very hot and dense medium.
Gravity worked hard to crush this dense medium to its enormous mass and small
diameter.
When the heat became too great there was a big explosion and the matter expanded
violently.
The contents of the known universe expanded explosively into existence from a hot,
dense state 13.7 billion years ago (NAEP 2009).
Gravity pulled the atoms together into gas clouds that eventually became stars, which
comprise young galaxies
Evidence for the Big Bang
There are 3 Main Evidence for the Big Bang Theory :
1. Cosmic Microwave Background Radiations – Leftover energy from Big
Bang, found in space all the time.
2. Hubble’s Law – The further away an object is in space, the faster it is
moving from the Earth.
3. Red Shirt – Almost all the galaxies in space are moving away from each
other. Suggests common starting point (puddle and rock)
Technology Used in Space Investigation
• Technology provides the basis for many new discoveries related to space and
the universe.
• Visual, radio and x-ray telescopes collect information from across the entire
electromagnetic spectrum;
• computers are used to manage data and complicated computations; space
probes send back data and materials from remote parts of the solar system;
• accelerators provide subatomic particle energies that simulate conditions in
the stars and in the early history of the universe before stars formed.
Telescopes
• 2 main types :
• 1 ) Land Telescope – Found on Earth and can be either Reflectors (Mirrors),
refractors (Lenses) or Radio Telescopes .
• Have to be far away from civilization and at high elevations to escape light pollution
and to reduce atmospheric blurring.
• 2) Space Telescopes – Found in space and collect other forms of radiation.
• Collect better images because they do not have to worry about light pollution and
atmospheric blurring
Other Cool Tech
• Satellites – Can be used for communication, telescopes, and asteroid
deflection and destruction in the future
• Planes – Currently being developed to investigate the atmosphere of planets
like Venus and the gas giants, and their moons.
• Rovers – Machines controlled either from Earth or a space station/space
ship to investigate a planet. Can be used to collect evidence about a planet or
asteroid.
Galaxy Formation
A Galaxy - is a large collections of stars and gas held together by GRAVITY
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There are billions of galaxies in the universe, and they are classified by size and shape.
The Milky Way is a spiral galaxy.
It has more than 100 billion stars and a diameter of more than 100,000 light years.
At the center of the Milky Way is a collection of stars bulging outward from the disk,
from which extend spiral arms of gas, dust and most of the young stars.
1 light year = the time distance light travels in one year.
Types of Galaxies
• 3 Types of Galaxies :
• 1) Spiral galaxies - Three main components: a bulge, disk, and halo The
bulge is a spherical structure found in the center of the galaxy. This feature
mostly contains older stars. The disk is made up of dust, gas, and younger
stars. The disk forms arm structures.
• http://www.astro.cornell.edu/academics/courses/astro201/galaxies/images.
htm
Types of Galaxies
• 2) Elliptical Galaxies - Elliptical galaxies are shaped like a spheriod, or elongated
sphere. In the sky, where we can only see two of their three dimensions, these galaxies
look like elliptical, or oval, shaped disks
• 3) Irregular Galaxies - regular galaxies have no regular or symmetrical structure.
• They are divided into two groups, Irr I and IrrII. Irr I type galaxies have HII regions,
which are regions of elemental hydrogen gas, and many Population I stars, which are
young hot stars. Irr II galaxies simply seem to have large amounts of dust that block
most of the light from the stars. All this dust makes is almost impossible to see
distinct stars in the galaxy.
Stars
• Early in the formation of the universe, stars formed out of clouds of hydrogen and helium and
clumped together by gravitational attraction into galaxies.
• When heated to a sufficiently high temperature by gravitational attraction, stars begin nuclear
reactions, which convert matter to energy and fuse the lighter elements into heavier ones.
• When heated to a sufficiently high temperature by gravitational attraction, stars begin nuclear
reactions, which convert matter to energy and fuse the lighter elements into heavier ones.
• All of the elements, except for hydrogen and helium, originated from the nuclear fusion
reactions of stars
Star Formation
• Step 1: initial collapse of an interstellar cloud (nebulae)
• gravity will always cause a contraction and subsequent collapse, which causes the temperature
and density to increase.
• Step 2: the cloud fragments into clumps – Internal turbulent motion keeps the star turning
and keeps it from collapsing. The temperature continues to rise. –Forms Protostar
• Step 3: to the main sequence – Depending on how much hydrogen fuel the star has the star will
take it its place on the main sequence and stay there until its depletes its hydrogen fuel.
• http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/starform.htm
Classification of Stars
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Stars are classified based on their :
1) Color
2) Size
3) Luminosity
4) Mass
Hertzprung-Russell Diagram
• A Hertzprung-Russell diagram can be used
to estimate the sizes of stars and predict how
stars will evolve.
• Most stars fall on the main sequence of the
H-R diagram, a diagonal band running from
the bright hot stars on the upper left to the dim
cool stars on the lower right
• A star’s mass determines the star’s place on
the main sequence and how long it will stay
there.
Life of a Star
• Patterns of stellar evolution are based on the mass of the star.
• Stars begin to collapse as the core energy dissipates.
• The nuclear fusion of Iron removes energy from the star and causes the star to
star cooling down.
• When the star runs out of hydrogen it will expand because it loses mass
therefore, the gravity is weaker.
• This causes the eventual collapse of the star or explosion of the star in a
supernova.